IconForge: Headless Icon Generation

[itsmeow]

Adds a new headless generation system to IconForge via rustg_iconforge_generate_headless:

/// Creates a single DMI or PNG using 'sprites' as a list of icon states / images.
/// This function is intended for generating icons with only a few states that have little in common with each other, and only one size.
/// For icons with a large number of states, potentially variable sizes, that re-use sets of transforms more than once, or that benefit from caching, use rustg_iconforge_generate.
/// sprites - follows the same format as rustg_iconforge_generate.
/// file_path - the full relative path at which the PNG or DMI will be written. It must be a full filepath such as tmp/my_icon.dmi or my_icon.png
/// flatten - boolean (0 or 1) determines if the DMI output will be flattened to a single frame/dir if unscoped (null/0 dir or frame values).
///
/// Returns a HeadlessResult, decoded to a BYOND list (always, it's not possible for this to panic unless rustg itself has an issue) containing the following fields:
/// list(
///     "file_path" = "tmp/my_icon.dmi" // [whatever you input returned back to you, null if there was a fatal error]
///     "width" = 32 // the width, which is determined by the first entry of 'sprites', null if there was a fatal error
///     "height" = 32 // the height, which is determined by the first entry of 'sprites', null if there was a fatal error
///     "error" = "[A string, null if there were no errors.]"
/// )
#define rustg_iconforge_generate_headless(file_path, sprites, flatten) json_decode(RUSTG_CALL(RUST_G, "iconforge_generate_headless")(file_path, sprites, "[flatten]"))

This system is intended for generating icons with only a few states that have little in common with each other, and only one size, as opposed to the traditional generation which is suitable for large batches that re-use icons regularly.

The new function is suitable for creating drop-in replacement for one-time icon operations and could be used for something like generating a minimap with DrawBox. Speed relative to native BYOND icons is not guaranteed due to the I/O cost and less optimization / caching, but it's likely to be faster for icons that are built with a large number of transforms in sequence, because it doesn't resolve the icon until it's converted.

Also fixes a bug where flattened icons could pollute the cache with incorrect data by splitting the caches for flattened and non-flattened icons.

Adds error-tests for icon generation using the new headless generator, checking for common error cases. Also tests headless generation for consistency with BYOND and regular batch generation.

not to mention that one could potentially combine this with get_flat_uni_icon to produce a speedier GFI

[AffectedArc07]

Is this iconforge getflaticon?

Please ignore

[itsmeow]

no...?